Method and apparatus for joining strip



Nov. .22, 1966 M. M. SEELOFF ETAL METHOD AND APPARATUS FOR JOINING STRIP 5 Sheets-Sheet 1 Filed Feb. 21, 1963 INVENTORS MELVIN M. SEELOFF JOSEPH H. COOPER ATTOR EY NOV. 1966 M. M. SEELOFF ETAL 3,286,342

METHOD AND APPARATUS FOR JOINING STRIP Filed Feb. 21, 1963 5 Sheets-Sheet 2 FIG. 3

FIG. 2

INVENTORS MELVIN M. SEELOFF JOSEPH H. COOPER f ATTZNEY FIG. 4A

Nov. 22, 1966 M. M. SEELOFF L METHOD AND APPARATUS FOR JOINING STRIP 5 Sheets-Sheet 5 Filed Feb. 21, 1963 FIG. 5

FIG. 5A-

FIG 6 INVENTORS MELVIN M. SEELOFF JOSEPH H. COOPER I I ATTO NEY Nov. 22, 1966 M. M. SEELOFF E TAL METHOD AND APPARATUS FOR JOINING STRIP 5 Sheets-Sheet 4 Filed Feb. 21, 1963 FIG. 6A

FIG. 7

HQ 7A INVENTORS MELVIN M. SEELOFF JOSEPH H. COOPER ATTORNEY Nov. 22, 1966 M. M. SEELOFF ET AL METHOD AND APPARATUS FOR JOINING STRIP 5 Sheets-Sheet 5 Filed Feb. 21, 1965 FIG.

INVENTORS MELVIN M. SEELOFF JOSEPH H. COOPE R ATTORNEY United States Patent 3,286,342 METHQD AND APPARATUS FQR JOINING STRIP Melvin M. Seeloff and Joseph H. Cooper, Warren, Ohio, assignors to The Taylor-Winfield Corporation, Warren, Ohio, a corporation of Ohio Filed Feb. 21, 1963, Ser. No. 260,104 16 Claims. (Cl. 29-482) This invention relates to improved apparatus for joining thin metal strip in general end-to-end relation to provide continuous strip for processing equipment such as tinning lines or for high speed forming or fabricating lines utilizing strip stock. The primary object of the invention is to further decrease the time required for the joining cycles and the complexity of the apparatus required while yet increasing the dependability thereof whereby strip lengths furnished in successive coils may be very rapidly and expeditiously joined to provide continuous strip at high speed with a minimum of periodic interruption time. The latter characteristic is highly beneficial in reducing strip loop storage space intermediate the joining apparatus and the processing or utilization line-a problem which is well known in the strip handling and feeding art.

We have heretofore, in our co-pending United States patent application Ser. No. 239,626, filed November 23, 1962, now Patent No. 3,235,703 contended that a narrow lap seam weld is the best type of joint for many applications primarily because of the speed with which it may be effected and because of its dependable quality. We have proposed an apparatus assembly movable with respect to overlapped strip and having twin shears operative to separately shear two overlapped strip pieces along offset lines. An overlap is thus maintained which is of precise and consistent dimension or extent. Coupled with the shearing means and following closely therebehind are seam welding electrode wheels to engage the sheared edges of the overlapped strip to scam weld the same together. Such shearing apparatus requires, of course, that the two strip lengths have consistent positional relation or that the shearing means be inverted when the positional relation of the strip lengths is changed or inverted. The latter alternative runs into apparatus complications, and it is acc0rdingly a more specific object of the present invent-ion to arrange for an improved strip handling method and associated apparatus embodying the double shear and welder assembly whereby the strip lengths to be joined are always uniformly related to each other. Thus, if the overlapped stock is viewed in the direction of shear wherein the lower cut is on the left and the upper cut is on the right, the extension of the lower strip is always to the right while the extension of the upper strip is to the left.

Yet another object of the invention is to provide in apparatus of the kind explained above an improved arrangement for temporarily retaining a leading end portion of a new strip length in positional readiness for being fed into the joining apparatus upon the running strip nearing the end of its length. This leading end portion is held in looped position to provide an adequate leading length of strip to span the two strip clamps which are provided in the joining apparatus and between which the aforementioned twin shears and electrode wheels move in effecting a joining operation. The looped length is allowed to expand out fiat for this purpose, in overlying relation to the tail end portion of the last running strip which has been stopped, and as will appear hereinafter we provide an additional shear at the entry side of the joining apparatus to trim away any rearwardly extending portion of the stopped strip which may interfere with the feeding of the looped new strip when the latter is stored below the plane of the stopped strip.

A further object of the invention is the provision of an improved arrangement for holding the croppings from the double shear free and clear of the sheared and welded strip until such croppings can be extracted or removed from the apparatus to thereby allow the welded strip to resume its longitudinal running movement immediately upon completion of the welding phase of the joining cycle and upon the opening of the welding clamps. A more specific object of the invention is the provision of an arrangement whereby said croppings may be shifted laterally with respect to the running strip while still being retained free and clear of the running strip so that an operator may thereafter manually remove the croppings from the joining apparatus without being endangered by the running strip.

The above and other objects and advantages of the invention will become apparent upon consideration of the following specification and the accompanying drawing wherein there is disclosed a preferred embodiment of the invention.

In the drawings:

FIGURE 1 is a fragmentary side elevation of a metal strip joining machine and associated strip feed apparatus utilizing the principles of our invention, the illustration showing a length of strip from a top payoff reel running through the machine while a length of strip from a bottom payoff reel is being held in readiness for quick entry into the machine when the top strip is paid off;

FIGURE 1A is a fragmentary side view of the feed apparatus and a few parts of the joining machine with strip from the bottom payoff reel running through the machine while strip from the top payoff reel is held in position for quick entry into the machine upon the bottom strip being paid off;

FIGURE 2 is a fragmentary end elevation of the machine of FIGURE 1;

FIGURE 3 is an end elevation, partly in section, of the trigersing double shear utilized in the machine of FIG- U E1;

FIGURES 4 and 4A show the positions of the parts and strip immediately after the last running strip (top strip in FIGURE 4 and bottom strip in FIGURE 4A) has been stopped and sheared on the entry side of the joining machine, the views showing the respected tailings being retracted;

FIGURES 5 and 5A show, respectively, the pre-held strip from the bottom and top payoff reels immediately after insertion in the joining machine preparatory to being oined to the tail end of the last running strip;

FIGURES 6 and 6A show, respectively, the leading end of the strip from the bottom and top payoff reel being oined to the tail end of the last running strip;

FIGURES 7 and 7A show, respectively, new strip from the bottom and top payoff reels running through the joining machine;

FIGURES 8 and 9 are fragmentary end and side elevations, respectively, of a modified form of exit strip clamp which may be used in the assembly of FIGURE 1 to hold the croppings from the double shear free and clear of the newly welded strip and to facilitate the removal of such croppings after the newly welded strip has started its longitudinal movement through the joining apparatus; and

FIGURE 10 is a face view of a slideable section of the movable platen of the clamp of FIGURES 8 and 9.

In common with the apparatus more specifically disclosed in the above-mentioned co-pending application, the joining machine included herein comprises a fixed base 10 on which is mounted an entry strip clamp 16 and a longitudinally spaced exit strip clamp 17. These clamps are arranged to be opened and closed by air cylinders 16C and 170, respectively, and it will be understood that they are tightly closed onto the overlapped strip pieces while the latter are being joined together.

Slideably mounted on the base for movement between and parallel with the clamps 16 and 17 is a C- shaped carrier 11 which mounts at its closed end, not shown, a welding transformer, also not shown, and which mounts on its outer free ends a lower resistance welding electrode wheel 12 and an upper similar wheel 13. The latter is arranged to be raised and lowered onto the work and to have welding pressure applied to it by a cylinder 15, and the vertical position of the bottom electrode 12 is arranged to be adjusted to compensate for wear by a suitable elevating mechanism 15'. Also in accordance with the disclosure of the above-mentioned copending application there is closely associated with the welding throat comprised of electrodes 12 and 13 a double shear denoted in its entirety by the reference numeral and shown herein more in detail in FIGURES 2 and 3. This unit is arranged to be raised and lowered by a cylinder 22 and is normally raised well above the plane of strip travel when strip is running through the joining machine. However, after the running strip is stopped and immediately before the next succeeding strip length is loaded into the machine, this unit is lowered so that the protruding portion of the cantilevered fiat tapered anvil 27 overlies the bottom or stopped strip. Anvil 27 is furnished with the carbide insert 30 providing upper and lower offset cutting edges 28 and 29, respectively, which are arranged to cooperate with the cutting edges 31 and 36 of the upper and lower rotary shear knives 32 and 35. The purpose of the arrangement is to permit the anvil 27 to enter in between the two ovelapped strip portions while the latter are held by the clamps 16 and 17 and upon subsequent traversing movement of the frame 11 to shear both the bottom strip and the top strip along parallel transverse but longitudinally offset lines while leaving the strip overlapped between these lines. The overlapped strip is then welded together by the closely following wheel electrodeslZ and 13.

The lower platens of the clamps 16 and 17 are normally fixed, the upper platens of these clamps being mechanically arranged to be raised and lowered by the cylinders 16C and 17C. In accordance with the present invention, we provide a strip shear at the entry end of the joining machine, this shear having a lower fixed knife blade 60, the upper cutting edge of which lies substantially in the plane of the top surfaces of the lower platens of the clamp 16 and 17. Cooperating with the shear knife 60 is an upper shear blade 61 which is mechanically arranged for vertical movement by cylinder 62. Immediately ahead of the shear 60, 61 is a strip supporting roll 63 which, together with a similar roll, not shown, positioned at the exit end of the machine establishes a free running plane for strip through the machine when the shear blade 61 and the upper platens of the clamps 16 and 17 are retracted or opened.

In furtherance of our principal object to effect strip joining in the least possible time we provide an upper payoff reel 64, and a lower payoff reel 65, both adapted to receive a coil of metal strip and both preferably arranged to be power driven in forward and reverse directions to facilitate threading of new strip and to retract sheared tailings of strip as will be hereinafter explained. Arranged to receive strip from the coil on upper reel 64 is a pair of pinch rolls 66 and a similar pair of pinch rolls 67 is provided for the lower reel 65. Intermediate the pinch rolls and the reels is a double shear 68 which is provided to crop off the normally battered beginning end1 of the strip of the coils which are loaded onto the ree s.

Positioned immediately beyond the pinch rolls 66 is a substantially horizontal plate-like support 69 provided to restrain a looped leading end portion of strip coming from the upper reel out of contact with strip running from the lower reel, the loop being provided, as shown in FIG- URES 1A and 4A, to provide a readily accessible strip length for quick insertion in the joining machine preparatory to making a joint with the paid out previously running coil of strip, all as will be more fully explained below. This loop is established and maintained not only by the support 69 but also by a bar-type of magnet 70 which is fixed with respect to the joining machine and which is adapted to temporarily secure the end extremity of the new strip. The proposed method of use of these parts 69, 70 is illustrated in FIGURES 1A and 4A.

Positioned immediately beyond the pinch rolls 67 is an upwardly inclined plate-like support 71 which, together with a bar-type of magnet 72, is adapted to hold a looped leading end portion of strip coming from the lower reel 65 out of contact with the strip running from the upper reel and to provide a readily accessible strip length for quick insertion in the joining machine when the upper strip length is paid out.

Built into the lower platen of entry clamp 16 and the upper platen of exit clamp 17 are suction cups 73 (see FIGURES 7 and 7A) which are suitably connected to a source of less than atmospheric air pressure and which operate to keep the scrap ends of the strips free from the running line of the strip after the shear 20 has completed its traverse and the strip joint has been made. There are a plurality of suction cups spread across each clamp so that the scrap will remain in contact with the inner faces of the platens of the clamps until the scrap is almost completely slid out of the opened clamps.

Considering now the operation of the above described apparatus, FIGURE 1 shows strip from the top uncoiler 64 running free through the pinch rolls 66, over the support rolls 63, and through the strip joining machine. During this running, the leading end of strip from a new coil which has been loaded on the bottom uncoiler 65 is first cropped off by the shear 68 after which the new end portion is fed through pinch rolls 67 and over the support 71 into a downwardly looped position with the end extremity of the strip being held by the magnet 72, all as shown in FIGURE 1. Sufficient stock is accumulated in the loop held between support 71 and magnet 72 to allow. for full loading of the joining machine in the next sequence now to be described.

When the running strip from the upper uncoiler 64- has almost deleted the supply of strip on this upper uncoiler, the line is stopped, the shear 60, 61 is actuated as shown in FIGURE 4, and the uncoiler 64 is reversed, also as shown in FIGURE 4, to extract the scrap tail end of this last running strip. As soon as the sheared end of this scrap clears the space between the flat support 69 and the supporting roll 63 the end of the new strip held by magnet 72 is drawn up and over the support roll 63 and threaded into the now opened shears 6t), 61 and clamp 16, 17, all as shown more clearly in FIGURE 5 of the drawing. Before this is done, however, the cylinder 22 (see FIG- URE 2) is actuated to place the shear anvil 27 in overlying contact with the stopped strip. The new strip threaded in as aforesaid overlies the top of the anvil 27. Now the clamps 16 and 17 are closed and the frame 11 begins its traverse to effect the double olfset lines of shear in the overlapped strip and the immediately following welding together of the resultant overlapped end portions. The latter is accomplished by the electrodes 12 and 13 and, of course, the cylinder 15 is first actuated to bring these electrodes together and to apply welding pressure therethrough as the electrodes move into engagement with the overlapped and aligned side edges of the strip.

The feeding of the looped front end portion of the strip from lower uncoiler 65 over the roll 63 and into the shear and clamps of the joining apparatus is now accomplished manually although it is contemplated that this in-feeding of the prepared (sheared) and stored strip length may'be accomplished mechanically with suitable automated equipment, necessitating perhaps some change in the holding devices. 1

Upon completion of the working traverse of the double shear 2t and the welder 12, 13, the clamps 16, 17 may be immediately opened and the running of strip restarted, this time from the lower uncoiler 65. The various parts are so related that when the clamps close onto the overlapped strip the strip is drawn down slightly, and when the clamps open the strip which is always under some tension will rise up free and clear of the bottom platens of the clamps and of the scrap end which remains drawn to the lower platen of clamp 16 by the suction cups 73 as above explained. Of course, the scrap end of the new strip coming from the bottom uncoiler 65 remains drawn to the upper platen of clamp 17 by the suction cups 73 built thereinto. These scrap pieces are removed by being slid out of the clamps fiatwise while yet retaining flat contact with the platens until they are substantially completely free of the platens. This avoids marking of the running strip which might be quite soft and highly finished.

In the embodiment of the strip clamp illustrated in FIGURES 8-10, the suction cups 73 of the above described embodiment of the invention are replaced by a construction illustrated in FIGURES 8-10 and now to be described. The exit strip clamp illustrated in these figures is designated generally by reference numeral 17 and if applied to the apparatus of FIGURE 1 would perform generally the function of clamp 17 of FIGURE 1. Thus, clamp 17' has a lower fixed platen 81 and a vertically movable upper platen 82 which is suitably guided for vertical movement with respect to the lower platen and which is arranged to be actuated by a vertical disposed cylinder 83'. Platen 82 is formed with a transversely disposed guiding groove 83 in which is slideably mounted a flat slab-like member 84.

Suitably adhered to the bottom face of slab 84 is a layer 85 of sheet rubber or of neoprene or the like which within its periphery has cutout portion 85A, 85B and 85C spaced along the extent of the slab 84 and transversely of the longitudinal path through the joining equipment as will be evident. Suitably formed in the slab 85 and individual to each of the recesses SSA-C are passageways 86 which have inlets in the recesses and which extend outwardly to ports 87 located on one end wall of the slab or slide 84. Ports 87 are connected through flexible hose loops 88 to individual sources of suction or pressures well below atmospheric. For a reason to be later described, independent suction sources are provided so that even though the partial vacuum in recess 85A is broken, for example by the withdrawal of spanning strip therefrom, a partial vacuum will be retained in each of the recesses 85B and 85C so long as the latter remain covered with strip.

Mounted on the end of the slide 84 opposite the ports 87 is a handle 89 by which the slide 84 may be manually moved transversely out of alignment with the general strip pass through the joining apparatus. The purpose of this is to move a side edge portion of the cropping well outwardly of the joined or Welded strip which lies in the apparatus so that even though such latter strip has already started its running movement through the apparatus the said side edge portion of the cropping may be safely engaged manually by the operator as a start toward withdrawing the cropping sideways out of the apparatus.

In the operating cycle of the joining apparatus utilizing the exit clamp of FIGURES 810, it will be understood that a partial vacuum will be applied through flexible conduits 88 to the recesses 85A- C at least by the time the shear of FIGURE 3 and the welding electrodes 12, 13 have about completed their operative traverse. At this time the slide 84 is fully retracted within the platen 82 and the latter platen is clamped down hard onto the overlapped strip held by the exit clamp with the rubber sheet 85 on the slide 84 overlying the top strip. This top strip becomes the cropping and immediately after completion of the welding traverse the exit clamp is opened and the platen 82 rises carrying with it the vacuumized slide 84 to which the cropping is adhered.

As stated above, the welded strip may be restarted immediately upon sufficient opening of the entry and exit clamps, and while such strip is running, the operator may partially withdraw the slide 84 and proceed to slide out the cropping. The end of the cropping nearest to the operator is well away from the dangerous edge of the running strip when the slide is Withdrawn so that the operator can safely grab the adjacent edge portion of the cropping to draw the same toward him. It should be noted that during such withdrawal that portion of the cropping which remains above the running strip will be held in upper position away from the running strip by the consecutive vacuumized recesses SSA-C. This avoids any danger of cobbling between the cropping and the running strip and also prevents any marking or scratchproduct. As soon as the cropping is completely removed, ing of the running strip which may be a highly finished product. As soon as the cropping is completely removed, the operator shoves the slide 84 back into fully retracted position in the platen 82 preparatory to the next cycle of operation.

It should be understood that in the complete joining assembly the lower platen of the entry strip clamp (16 in FIG. 1) may have built into it a vacuumized slide identical to that described above to similarly facilitate the removal of the cropping which is formed of the bottom strip of the overlapped strip held in the entry clamp during the joining cycle. As explained above, the unrestricted pass plane of the running strip through the apparatus is positioned considerably above the top surface of the lower platen of the entry clamp so that after a joint is made, the entry clamp opened and any tension is applied to the joined strip the joined strip will rise above the cropping left in the entry clamp and so long as this cropping is held flat down against the bottom platen and the sliding section thereof by the vacuumized spaces formed in such section it will not come in contact with the running strip to be cobbled therewith or to scratch or otherwise damage the same. Again, the slide in the entry clamp platen is provided with a handle so that the operator can move the adjacent edge portion of the cropping toward him to permit the safe removal of the cropping as described above in connection with the exit clamp.

When the running strip from the bottom uncoiler 65 is about all paid off the bottom uncoiler the line is again stopped to permit the above described sequence of operation to be repeated as illustrated in FIGURES 1A, 4A, 5A, and 6A to restore a running supply of strip, this time from the top uncoiler 64 as illustrated in FIGURE 7A.

It should now be apparent that we have provided an improved method for handling and preparing strip in the joining thereof in general end-to-end relation and improved apparatus for carrying out the method which accomplished the objects initially set out. By providing the shear (60, 61) immediately ahead of the entry strip clamp it is most expedient to always lay the new incoming strip on top of the tail end portion of the previously running strip so that the positional relation of the strip lengths prior to joining is always the same. This permits the double shear of FIGURE 3 to retain its same orientation in each successive strip joining cycle whereby the overall apparatus is materially simplified. Further, by providing readily releasable means to retain the looped forward end portions of the new strip the feeding of this new strip into the joining machine is very quickly and easily accomplished upon stopping of the running strip and the shearing and withdrawal of the trailing end thereof. In this manner the new strip may be connected to the previously slitting knives operated by air motors, for example. In fact, the principles of the present invention are applicable to any specific joining apparatus wherein the strips to be joined should have a consistent positional relation in each succeeding joining cycle. Reference should therefore be had to the appended claims in determining the scope of our invention.

We claim:

1. In apparatus for joining strip in general end-to-end relation and having a pair of longitudinally spaced entry and exit strip clamps, said clamps in their open position defining a passage of said strip, as Well as a combined double shear assembly and seam Welder assembly comprising three cutting means, one of said cutting means being positioned above said passage, the second cutting means being below said passage and longitudinally offset from said first cutting means and a third cutting means being positioned between the overlapped portion of two strips to be joined and having two cutting surfaces, one cutting surface cooperating with said first cutting means and the second cutting surface cooperating with said second cutting means transversely movable between said clamps and wherein said shear for shearing along offset lines overlapped strip ends held in said clamps, the improvement comprising a strip shear positioned at the entrance end of said entry clamp in a longitudinal direction to crop off the tail end of a strip length extending through said clamps and beyond said exit clamp and means for retracting the tail end of said strip, to thereby facilitate the longitudinal entry into said clamps of the leading end portion of a second strip length at the entrance end of said entry clamp with said leading end portion overlying the first mentioned strip length.

2. Apparatus according to claim 1 further including means to feed strip into said clamps from a pair of vertically spaced sources and along paths which converge in the direction of said entry clamp, the arrangement being such that upon the strip running from the upper of said sources becoming substantially depleted it may be stopped and said last mentioned shear and retracting means actuated immediately to clear the way for the entry into said clamps of the leading end of a second strip length coming from the lower of said sources.

3. Apparatus according to claim 2 further including means to temporarily hold a leading end portion of strip near the entrance end of said entry clamp and coming from either one of said sources while strip is being passed off from the other of said sources and running through said clamps, said means to hold being operative to retain a loop in said leading end portion of strip of sufficient length to allow said leading end portion to be threaded into said clamps without paying ofi? further strip from the connected source.

4. Apparatus according to claim 3 further characterized in that said holding means comprises a pair of pinch rolls through which the strip is fed from the source, a flat table-like support extending outwardly and longitudinally beyond the exit side of said pinch rolls and operative to support strip in flat overlying relation, and means vertically offset with respect to said fiat support to secure the extreme end portion of strip extending longitudinally beyond said pinch rolls and fiat support.

5. Apparatus according to claim 4 further characterized in that said offset securing means is a magnet.

comprising a strip shear positioned at the entrance end of said entry clamp in a longitudinal direction to crop oft" the tail end of a strip length extending through said clamps and beyond said exit clamp, and means for retracting the tail end of said strip to thereby facilitate the longitudinal entry into said Clamps of the leading end portion of a sec- 0nd strip length extending at the entrance end of said entry clamp with said leading end portion overlying the first mentioned strip length.

7. Apparatus according to claim 6 further including means to feed strip into said clamps from a pair of vertically spaced sources and along paths which converge in the direction of said entry clamp, the arrangement being such that upon the strip running from the upper of said sources becoming substantially depleted it may be stopped and said shear and retracting means actuated immediately to clear the way for the entry into said clamps of the leading end of a second strip length coming from the lower of said sources.

8. Apparatus according to claim 7 further including means to temporarily hold a leading end portion of strip ahead of said entry clamp and coming from either one of said sources while strip is being passed ofi from the other of said sources and running through said clamps, said means to hold being operative to retain a loop in said leading end portion of strip of sufiicient length to allow said leading end portion to be threaded into said clamps without paying off further strip from the connected source.

9. Apparatus according to claim 8 further characterized in that said holding means comprises a pair of pinch rolls through which the strip is fed from the source, a flat table-like support extending outwardly and longitudinally beyond the exit side of said pinch rolls and operative to support strip in flat overlying relation, and means vertically offset with respect to said fiat support to secure the extreme end portion of strip extending longitudinally beyond said pinch rolls and flat support.

10. Apparatus according to claim 9 further characterized in that said offset securing means is a magnet.

11. The method of joining strip fed alternately from a pair of coil sources which consists of cropping off the leading end portion of strip from one of the coils and gathering a loop of the remaining head end portion of the strip from the said one of the coils while strip is being paid off from the other of said coils, interrupting the movement of strip from the said other of said coils when said other coil is about depleted, transversely shearing the last mentioned strip, retracting said last mentioned strip, overlaying said loop portion of new strip onto the tail end portion of the first strip beyond the line of shear, and thereafter joining said overlaid strip to said tail end portion of strip.

12. The method of claim 11 including the further steps of shearing the overlapped new strip and tail end of strip along transversely extending but longitudinally spaced lines of shear to provide an overlap in the new and old strip of uniform and control dimension, and immediately thereafter seam welding said uniformly overlapped strip together.

13. In apparatus for joining strip wherein overlapped portions of the strip lengths to be joined are held in a strip clamp and wherein the end portion of at least one of the strip lengths is cropped ofr in the joining process while said end portion remains under pressure engagement by one of the platens of the clamp, the improvement comprising a recess in the clamping face of said one of said platens and means to apply a partial vacuum to said recess whereby said cropping adheres to said one of said platens when the clamp is opened to thereby move said cropping away from the joined strip.

14. Apparatus according to claim 13 further characterized in that said one of said platens is provided with a face section which is slideable parallel with respect to the plane of the joined strip when the clamp is opened and in a direction transversely to the longitudinal axis of the joined strip, and said recess being positioned in said section whereby said cropping may be moved transversely of said axis while being held flat free and clear of the joined strip.

15. Apparatus according to claim 13 further characterized in that said recess is formed of a cutout portion of a rubber-like sheet adhered to the face of the said one of said platens.

16. Apparatus according to claim 13 further including a pair of separate recesses in the face of said one of said platens spaced transversely with respect to the longitudinal axis of the joined strip, and means to vacuumize said recesses independently whereby upon opening of the clamp the cropping which is adhered to the face of the said one of said platens may be slid oif said face in a direction transverse to said axis while that portion of the cropping which remains in contact with the face is adhered thereto by the vacuum'ized recesses in succession.

References Cited by the Examiner UNITED STATES PATENTS 2,369,830 2/1945 Johnson et a1. 219-78 JOHN F. CAMPBELL, Primary Examiner.

M. L. FAIGUS, Assistant Examiner. 

6. IN APPARATUS FOR JOINING STRIP IN GENERAL END-TO-END RELATION AND HAVING A PAIR OF LONGITUDINALLY SPACED ENTRY AND EXIT STRIP CLAMPS AS WELL AS MEANS MOVABLE TRANSVERSELY OF THE STRIP HELD IN SAID CLAMPS TO JOIN SAIDS STRIP INTO A SUBSTANTIALLY CONTINUOUS LENGTH, THE IMPROVEMENT COMPRISING A STRIP SHEAR POSITIONED AT THE ENTRANCE END OF SAID ENTRY CLAMP IN A LONGITUDINAL DIRECTION TO CROP OFF THE TAIL END OF A STRIP LENGTH EXTENDING THROUGH SAID CLAMPS AND BEYOND SAID EXIT CLAMP, AND MEANS FOR RETRACTING THE TAIL END OF SAID STRIP TO THEREBY FACILITATE THE LONGITUDINAL ENTRY INTO SAID CLAMPS OF THE LEADING END PORTION OF A SECOND STRIP LENGTH EXTENDING AT THE ENTRANCE END OF SAID ENTRY CLAMP WITH SAID LEADING END PORTION OVERLYING THE FIRST MENTIONED STRIP LENGTH. 